In addition to her sons' filing, Franklin's niece has asked the court to appoint her as a personal representative of the estate, the Detroit Free Press reported.
It said under Michigan law, if an unmarried person dies without a will, his or her assets are divided equally among any children.

Franklin's lawyer has represented her in entertainment matters for nearly three decades, and told the paper that he constantly asked her to do a trust, but she never got around to it.

"I was after her for a number of years to do a trust," Los Angeles attorney Don Wilson told the paper. "It would have expedited things and kept them out of probate and kept things private."

Wilson is Franklin's attorney in copyright matters, song publishing and record deals, and will be consulted on estate planning purposes. He said while he doesn't have a dollar figure on the value of her assets, the lack of a will means the finances will become public in Oakland County Probate Court.

"I just hope (Franklin's estate) doesn't end up getting so hotly contested," Wilson said. "Any time they don't leave a trust or will, there always ends up being a fight."

CNN has reached out to Wilson for more details.

Franklin's funeral will be held on August 31 in Detroit, with the service for family and friends planned for 10 a.m. ET the same day.

Public viewings will be held August 28 and 29 from 9 a.m. to 9 p.m. at the Charles H. Wright Museum of African American History in Detroit.